Household or industrial products which contain active chemicals and ingredients often release gases when packaged in containers. As a result, pressure differences may build up between the inside of a closed container and the ambient pressure. If these pressure differences are not adequately resolved, then over time the container may swell, distort or even rupture and leak its contents. Thin-walled, partially flexible containers are particularly sensitive to the problem. Fluctuations in temperature and altitude during shipping or storage may also exacerbate the problem.
One approach to the problem of pressure build up involves the incorporation of selective barrier materials which are impermeable to liquids, but permeable to gases. GB 1 464 344 describes a self-venting closure comprising a gas-permeable membrane covering an orifice to the exterior. EP 593 840 discloses a container made of a thermoplastic material comprising a network of microchannels. This network of microchannels is permeable to gases, but not to liquids.
One drawback of the above approach is that the membranes or microchannels may lose at least part of their gas-permeability if they come into contact with liquid product inside the container. Furthermore, liquid products which are viscous or which have some affinity for the membranes or microchannels may adhere to them or block them following such contact instead of draining away back into the container package. Therefore the container loses venting capacity. There are many instances which can lead to such contact, such as the product agitation which normally occurs during shipment and transportation, or tilting or inversion of the container itself during storage.
It is an object of the present invention to provide an improved container for the packaging of fluent products which off-gas, which provides for venting of the container body independently of the orientation of the container, whilst retaining the product within the container body.
Another object of the invention is to provide an improved container for the packaging of viscous or semisolid products (such as gels, pastes, creams or lotions) which off-gas.